DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Amendment
Applicant’s amendment has been entered. Claims 1-7, 9-14, and 16-21 are pending. Claims 8 and 15 are canceled. Changes to the specification have overcome the objections to the specification for minor informalities. Adding the word “aid” to claim 16 has overcome the objection to claim 16 for minor informalities. Deleting “that is sized to substantially reside in interstitial spaces of the aluminum alloy powder” from claim 17 and canceling claim 15 has overcome the rejections under 35 USC 112(b).
Claim Interpretation
Both claim 1 and claim 17 claim “the continuous flow of gas consists essentially of nitrogen”. “The transitional phrase "consisting essentially of" limits the scope of a claim to the specified materials or steps "and those that do not materially affect the basic and novel characteristic(s)" of the claimed invention” (MPEP 2111.03(III) emphasis in original). “For the purposes of searching for and applying prior art under 35 U.S.C. 102 and 103, absent a clear indication in the specification or claims of what the basic and novel characteristics actually are, "consisting essentially of" will be construed as equivalent to "comprising." “ (MPEP 2111.03(III)). Regarding the chemical identity of the supplied gas/atmosphere in the sintering step, the present disclosure states: “the green part is subjected to a binder burnout and then a sintering process. The sintering process involves heating the green part under a continuous high flow of nitrogen gas for a time and at a temperature sufficient for aluminum powder in the green part to reach a super-solidus state, sinter together and produced a high density aluminum part” [0031] and “[i]t is important that the heating step is conducted under a continuous high flow of nitrogen gas. The atmosphere surrounding the green part should be primarily composed of nitrogen with no appreciable amount of oxygen. The continuous high flow of nitrogen flow over the green part should be at least about 5 SCFH (standard cubic feet per hour) and may go up to about 80 SCFH or greater. As the flow rate of nitrogen increases, the economics of producing the part may become more undesirable. In some embodiments the continuous high flow of nitrogen may be at least about 10 SCFH, still other embodiment greater than about 20 SCFH, and in additional embodiments greater than about 40. In some embodiments, the continuous flow of nitrogen may range from about 5 SCFH to about 40 SCFH. Using the process of the present invention, densities of 95% or greater are obtained, and in additional embodiment at least about 97%. Surprisingly, the high densities of 99% or greater required the use of a continuous high flow of nitrogen over the green parts during sintering. Other common sintering atmospheres, such as argon, hydrogen, or mixture of nitrogen and hydrogen were not effective at achieving densities of 99% or greater.” [0032]. Within this description, the only gas component, which the disclosure unambiguously excludes is oxygen; therefore, the limitation “the continuous flow of gas consists essentially of nitrogen” will be interpreted to exclude oxygen from the continuous flow of gas. The statement “[o]ther common sintering atmospheres, such as argon, hydrogen, or mixture of nitrogen and hydrogen were not effective at achieving densities of 99% or greater” in paragraph [0032] in the specification is sufficient to provide support for a continuous flow of gas which consists of nitrogen, if applicant chooses to amend the claim as such, but this statement in the specification is not sufficient to show that any amount of argon or hydrogen or gas other than oxygen would materially affect the basic and novel characteristics of the invention.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 1-7, 9-14, and 17-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Liu (US7517492) in view of Myers (Myers, Neal, and Randall German. "Rapid Prototyping of Aluminum by Selective Laser Sintering." Metal Powder Deposition for Rapid Manufacturing: Proceedings of the 2002 International Conference on Metal Powder Deposition for Rapid Manufacturing. Metal Powder Industries Federation, 2002) and Xiao (CN110405214A). Liu is cited in the IDS filed July 4, 2023. Myers and Xiao are cited in prior office action(s). References to Xiao are directed to the English-language translation which accompanied prior office action(s).
Regarding claim 1, Liu discloses a method for producing a densified aluminum part (sintered aluminum article column 1 lines 17-20, column 3 lines 20-22). Liu discloses forming a green part (3DP process printed article) from build powder and a binder (column 6 lines 35-53). Liu discloses that the build powder comprises aluminum alloy powder comprising aluminum alloy particles (column 3 lines 54-58). Liu exemplifies aluminum alloy 6061 (column 4 lines 46-60, column 9 lines 18-19, 39-40, 62-63, column 10 lines 7-8), which Liu discloses has an aluminum alloy composition comprising a magnesium content of 0.89 wt% of the aluminum alloy composition (column 9 lines 19-22). A magnesium content of 0.89 weight% lies within the claimed range from about 0.5 to about 5 weight%. Liu discloses that the build powder comprises a densification aid (sintering aid) mixed with the aluminum alloy powder (column 6 lines 6-11, column 7 lines 60-63, claim 6).
Liu discloses densifying the green part by heating the green part under nitrogen gas (column 6 lines 58-63, column 7 lines 15-38). Liu discloses a sintering atmosphere “primarily of nitrogen” with water and “minor amounts of other constituents, so long as they do not interfere with the sintering of the aluminum powder” as the constituents of the provided sintering gas as the only other disclosed constituents of the sintering gas (column 7 lines 34-48), thereby disclosing a sintering environment wherein the deliberately provided gas is primarily nitrogen and does not comprise oxygen gas, thereby disclosing a sintering gas consisting essentially of nitrogen, in view of direction provided in the present disclosure as filed. Liu discloses that the sintering is supersolidus liquid phase sintering, or, as when a sintering aid is used, liquid phase sintering (column 7 lines 19-21). As supersolidus sintering (as opposed to complete melting) is a sintering which by definition occurs between solidus and liquid temperature of the sintered material, Liu discloses that the densifying comprises heating to a sintering temperature between the solidus and liquid temperature of the aluminum alloy. Liu further discloses that sintering with a sintering aid promotes reaction-assisted (attacks the alumina film) super-solidus liquid phase sintering (column 1 line 64 to column 2 line 13). Liu discloses that the densified aluminum part (sintered article) has a relative density of at least about 60%; more preferably, a relative density of at least about 75%; even more preferably, a relative density of at least about 85%; and most preferably a relative density of at least about 95% (column 5 lines 30-35). Liu discloses that the parameters can be adjusted to arrive at a desired relative density (column 5 lines 23-30). The most preferred range of at least about 95% discloses by Liu (column 5 lines 23-30) directly meets the density range of at least 95%, and the broader ranges of relative densities disclosed by Liu (column 5 lines 30-35) overlap a range of at least 95%. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Liu is silent on the amount and relative sizes of the densification (sintering) aid, but Liu explicitly directs readers to the Myers reference regarding background knowledge of powder mixtures comprising aluminum and a sintering aid (column 1 line 64 to column 2 line 11).
Myers teaches producing a densified aluminum part (aluminum powder material) (abstract, page 235 Experimental Procedure section). Myers teaches forming a green part from build powder and a binder (Table V, abstract, page 235 Experimental Procedure Section). Myers forms green test slugs comprising 2% by weight binder (page 235 Experimental Procedure Section, page 238 Results and Discussion section, Table III), and forms example green parts with 4% by weight binder (page 235 Experimental Procedure Section, Page 239 Results and Discussion section Table V). Myers teaches that the build powder comprises aluminum alloy powder comprising aluminum alloy particles and having an aluminum alloy composition of alloy 6061 aluminum (“-170 mesh 6061” Table I, page 235 Experimental Procedure). Myers teaches that the build powder comprises a densification aid mixed with the aluminum alloy powder (tin (Sn) and/or magnesium (Mg) Abstract, Table II, abstract on page 232 and Background section on page 233 establish Sn and Mg as sintering aids). Myers teaches examples comprising 2% by weight Mg mixed with 6061 alloy and a combination of 2% Mg and 1% Sn by weight% mixed with 6061 alloy (Tables II, IV, page 238 Results and Discussion section), thereby teaching amounts of 2% and 3% densification(sintering) of the build powder. Myers teaches Mg powder particles have an average particle size (D50) of 41.6 microns; Sn powder particles have an average particle size (D50) of 10.6 microns, and 6061 alloy particles have an average particle size (D50) of 42.3 microns (Table I). Myers teaches densifying the green part by heating the green part under a continuous flow of nitrogen gas (flowing nitrogen gas, abstract) (page 235 Experimental Procedure section, page 239 Results and Discussion section). Myers teaches that sintering aluminum material with a sintering aid causes reaction-assisted liquid-phase sintering (page 233 Background section). Myers teaches that the sintered aluminum part has nearly full density (Table III, page 236 Results and Discussion section, page 241 Summary).
Both Liu and Myers teach similar processes for producing sintered 6061 alloy parts comprising a sintering aid.
In order to perform the embodiment comprising a densification (sintering) aid disclosed by Liu, applied above, it would have been necessary for one of ordinary skill in the art, at the time of filing, to supply the densification powder particles in some proportion and some particle size. Considering Liu explicitly cites Myers for sintering with a sintering aid (column 1 line 64 to column 2 line 11) in determining sintering aid parameters for the process disclosed by Liu, it would have been obvious for one of ordinary skill in the art at the time of filing to select sintering aid proportions of 2-3% and particle sizes which Myers teaches as effective for sintering aids for 6061 aluminum alloys (Tables I-II, page 238 Results and Discussion section), thereby predictably proportioning feed material in the process disclosed by Liu in amounts suitable for liquid phase sintering taught by both Liu (column 7 lines 15-38) and Myers (page 233). Both the significantly smaller Sn powder size and the slightly smaller Mg particle size relative to the alloy powder taught by Myers (Table I) meet the relative particle size limitation recited in claim 1.
Liu discloses that the green article has about 10% by volume binder (column 6 lines 46-50). Liu does not teach weight percentages of the binder, and Liu does not teach results of varying binder amounts. Liu further does not exemplify embodiments comprising binder. Myers teaches embodiments wherein green article comprises 2% binder by weight and embodiments wherein the green article comprises 4% binder by weight (page 235 Experimental Procedure Section, pages 238-239 Results and Discussion section, Tables III, V). Myers teaches that the amount of binder in the manufactured part affects the performance of the part (page 238). Considering Liu does not disclose results, reasons, or specific examples for setting a binder to the disclosed volume fraction, whereas Myers teaches and exemplifies specific binder proportions and Myers teaches that the binder proportions affect results (page 238), in order to ensure effective performance of the formed part, it would have been obvious to one of ordinary skill in the art at the time of filing to form the green part with 2% or 4% by weight binder, which Myers teaches as effective for producing such sintered aluminum parts (pages 235-236, 238), and which Myers teaches affects the performance of the formed part (page 238), thereby predictably forming a part with desired density and mechanical properties (pages 236, 238-239, Tables III, IV). 2% and 4% by weight are both within the claimed range of less than 5% by weight binder.
Liu discloses that where a binder has been used in forming the aluminum powder into a shape, the heating cycle is controlled to permit the binder to be removed (column 7 lines 31-33), and Myers teaches that gas flow can affect part distortion (page 241 Summary section). Liu in view of Myers does not disclose that the heating the green part (printed article) under gas consisting essentially of nitrogen, applied above, comprises heating the green part under a continuous flow consisting essentially of nitrogen gas of at least 5 standard cubic feet per hour (SCFH).
Xiao teaches a method for producing a densified part (claim 1, [0001], [0019]). Xiao teaches forming a green part (billet) from build powder and a binder [0012], [0043], [0068]. Xiao teaches that the build powder comprises an alloy powder comprising alloy particles (stainless steel powder, as opposed to particles of constituent elements) [0044]. Xiao teaches densifying the green part by heating the green part under a continuous flow of nitrogen gas [0015-17], [0023-25], [0049-59]. Xiao teaches supplying the nitrogen flow at rates of 20L/min to 45L/min at stages of the sintering [0052-53]. Xiao teaches that the flow of nitrogen maintains the nitrogen equilibrium allowing nitrogen to enter pores [0052-53], which Xiao teaches allows more densely sintering as sintering temperature rises [0054]. Xiao further teaches heating for binder removal under a flow of nitrogen gas of 10-100 L/min (claim 6, [0025]).
Both Xiao and Liu in view of Myers, applied above teach producing a part by forming a green part from build material comprising binder and alloy powder particles and sintering under nitrogen gas.
It would have been obvious for one of ordinary skill in the art at the time of filing to provide the gas consisting essentially of nitrogen in the method disclosed by Liu in view of Myers, applied above, at a continuous flow rate of 20-45 L/min because Xiao teaches that providing nitrogen in a sintering step at 20-45 L/min allows more densely sintering as sintering temperature rises [0054]. Further, considering Xiao teaches that a nitrogen flow of 10-100 L/min as suitable conditions for binder removal (claim 6, [0025]), a range of 20-45 L/min would predictably facilitate residual binder removal, which Liu discloses controlling in the heating step (column 7 lines 31-33). 20-45 L/min is equivalent to 42.4-95.3 cubic feet per hour, which meets a range of at least 5 SCFH.
Regarding claim 17, Liu discloses a method for producing a densified aluminum part (sintered aluminum article column 1 lines 17-20, column 3 lines 20-22). Liu discloses forming a green part (3DP process printed article) by binder jet additive manufacturing from build powder and a binder (column 6 lines 35-53). Liu discloses that forming the green part results in 30-60% of the volume of the green part of powder (printed article) (column 6 lines 47-49). As relative green density of a porous article is the volume percentage of the article which is not void space, the 30-60% volume disclosed by Liu (column 6 lines 47-49) overlaps a range of densities of a green part of about 50% to about 65%. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Liu discloses that the build powder comprises aluminum alloy powder comprising aluminum alloy particles (column 3 lines 54-58). Liu exemplifies aluminum alloy 6061 (column 4 lines 46-60, column 9 lines 18-19, 39-40, 62-63, column 10 lines 7-8), which Liu discloses has an aluminum alloy composition comprising a magnesium content of 0.89 wt% of the aluminum alloy composition (column 9 lines 19-22); therefore, Liu discloses that the build powder comprises: an aluminum 6061 alloy powder comprising aluminum 6061 alloy particles and having an aluminum alloy composition comprising a magnesium content of 0.89%. Liu discloses that the build powder comprises a densification aid (sintering aid) mixed with the aluminum alloy powder (column 6 lines 6-11, column 7 lines 60-63, claim 6). Liu discloses that the densification (sintering) aid is selected from the group consisting of tin and magnesium (column 6 lines 6-11, claim 7).
Liu discloses densifying the green part by heating the green part under nitrogen gas (column 6 lines 58-63, column 7 lines 15-38). Liu discloses a sintering atmosphere “primarily of nitrogen” with water and “minor amounts of other constituents, so long as they do not interfere with the sintering of the aluminum powder” as the constituents of the provided sintering gas as the only other disclosed constituents of the sintering gas (column 7 lines 34-48), thereby disclosing a sintering environment wherein the deliberately provided gas is primarily nitrogen and does not comprise oxygen gas, thereby disclosing a sintering gas consisting essentially of nitrogen, in view of direction provided in the present disclosure as filed. Liu discloses that the sintering is supersolidus liquid phase sintering, or, as when a sintering aid is used, liquid phase sintering (column 7 lines 19-21). As supersolidus sintering (as opposed to complete melting) is a sintering which by definition occurs between solidus and liquid temperature of the sintered material, Liu discloses that the densifying comprises heating to a sintering temperature between the solidus and liquid temperature of the aluminum alloy. Liu further discloses that sintering with a sintering aid promotes reaction-assisted (attacks the alumina film) super-solidus liquid phase sintering (column 1 line 64 to column 2 line 13). Liu discloses that the densified aluminum part (sintered article) has a relative density of at least about 60%; more preferably, a relative density of at least about 75%; even more preferably, a relative density of at least about 85%; and most preferably a relative density of at least about 95% (column 5 lines 30-35). Liu discloses that the parameters can be adjusted to arrive at a desired relative density (column 5 lines 23-30). The most preferred range of at least about 95% discloses by Liu (column 5 lines 23-30) directly meets the density range of at least 95%, and the broader ranges of relative densities disclosed by Liu (column 5 lines 30-35) overlap a range of at least 95%. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Liu is silent on the amount of the densification (sintering) aid, but Liu explicitly directs readers to the Myers reference regarding background knowledge of powder mixtures comprising aluminum and a sintering aid (column 1 line 64 to column 2 line 11).
Myers teaches producing a densified aluminum part (aluminum powder material) (abstract, page 235 Experimental Procedure section). Myers teaches forming a green part from build powder and a binder (Table V, abstract, page 235 Experimental Procedure Section). Myers forms green test slugs comprising 2% by weight binder (page 235 Experimental Procedure Section, page 238 Results and Discussion section, Table III), and forms example green parts with 4% by weight binder (page 235 Experimental Procedure Section, Page 239 Results and Discussion section Table V). Myers teaches that the build powder comprises aluminum alloy powder comprising aluminum alloy particles and having an aluminum alloy composition of alloy 6061 aluminum (“-170 mesh 6061” Table I, page 235 Experimental Procedure). Myers teaches that the build powder comprises a densification aid mixed with the aluminum alloy powder (tin (Sn) and/or magnesium (Mg) Abstract, Table II, abstract on page 232 and Background section on page 233 establish Sn and Mg as sintering aids). Myers teaches examples comprising 2% by weight Mg mixed with 6061 alloy and a combination of 2% Mg and 1% Sn by weight% mixed with 6061 alloy (Tables II, IV, page 238 Results and Discussion section), thereby teaching amounts of 2% and 3% densification(sintering) of the build powder. Myers teaches densifying the green part by heating the green part under a continuous flow of nitrogen gas (flowing nitrogen gas, abstract) (page 235 Experimental Procedure section, page 239 Results and Discussion section). Myers teaches that sintering aluminum material with a sintering aid causes reaction-assisted liquid-phase sintering (page 233 Background section). Myers teaches that the sintered aluminum part has nearly full density (Table III, page 236 Results and Discussion section, page 241 Summary).
Both Liu and Myers teach similar processes for producing sintered 6061 alloy parts comprising a sintering aid.
In order to perform the embodiment comprising a densification (sintering) aid disclosed by Liu, applied above, it would have been necessary for one of ordinary skill in the art, at the time of filing, to supply the densification powder particles in some proportion and some particle size. Considering Liu explicitly cites Myers for sintering with a sintering aid (column 1 line 64 to column 2 line 11) in determining sintering aid parameters for the process disclosed by Liu, it would have been obvious for one of ordinary skill in the art at the time of filing to select sintering aid proportions of 2-3% and particle sizes which Myers teaches as effective for sintering aids for 6061 aluminum alloys (Tables I-II, page 238 Results and Discussion section), thereby predictably proportioning feed material in the process disclosed by Liu in amounts suitable for liquid phase sintering taught by both Liu (column 7 lines 15-38) and Myers (page 233). Both the significantly smaller Sn powder size and the slightly smaller Mg particle size relative to the alloy powder taught by Myers (Table I) meet the relative particle size limitation recited in claim 17.
Liu discloses that the green article has about 10% by volume binder (column 6 lines 46-50). Liu does not teach weight percentages of the binder, and Liu does not teach results of varying binder amounts. Liu further does not exemplify embodiments comprising binder. Myers teaches embodiments wherein green article comprises 2% by weight and embodiments wherein the green article comprises 4% by weight (page 235 Experimental Procedure Section, pages 238-239 Results and Discussion section, Tables III, V). Myers teaches that the amount of binder in the manufactured part affects the performance of the part (page 238). Considering Liu does not disclose results, reasons, or specific examples for setting a binder to the disclosed volume fraction, whereas Myers teaches and exemplifies specific binder proportions and teaches that the binder proportions affect results (page 238), in order to ensure effective performance of the formed part, it would have been obvious to one of ordinary skill in the art at the time of filing to form the green part with 2% or 4% by weight binder, which Myers teaches as effective for producing such sintered aluminum parts (pages 235-236, 238), and which Myers teaches affects the performance of the formed part (page 238), thereby predictably forming a part with desired density and mechanical properties (pages 236, 238-239, Tables III, IV). 2% and 4% by weight are both within the claimed range of less than 5% by weight binder.
Liu discloses that where a binder has been used in forming the aluminum powder into a shape, the heating cycle is controlled to permit the binder to be removed (column 7 lines 31-33), and Myers teaches that gas flow can affect part distortion (page 241 Summary section). Liu in view of Myers does not disclose that the heating the green part (printed article) under gas consisting essentially of nitrogen, applied above, comprises heating the green part under a continuous flow consisting essentially of nitrogen gas of at least 20 standard cubic feet per hour (SCFH).
Xiao teaches a method for producing a densified part (claim 1, [0001], [0019]). Xiao teaches forming a green part (billet) from build powder and a binder [0012], [0043], [0068]. Xiao teaches that the build powder comprises an alloy powder comprising alloy particles (stainless steel powder, as opposed to particles of constituent elements) [0044]. Xiao teaches densifying the green part by heating the green part under a continuous flow of nitrogen gas [0015-17], [0023-25], [0049-59]. Xiao teaches supplying the nitrogen flow at rates of 20L/min to 45L/min at stages of the sintering [0052-53]. Xiao teaches that the flow of nitrogen maintains the nitrogen equilibrium allowing nitrogen to enter pores [0052-53], which Xiao teaches allows more densely sintering as sintering temperature rises [0054]. Xiao further teaches heating for binder removal under a flow of nitrogen gas of 10-100 L/min (claim 6, [0025]).
Both Xiao and Liu in view of Myers, applied above teach producing a part by forming a green part from build material comprising binder and alloy powder particles and sintering under nitrogen gas.
It would have been obvious for one of ordinary skill in the art at the time of filing to provide the nitrogen in the method disclosed by Liu in view of Myers, applied above, at a continuous flow rate of 20-45 L/min because Xiao teaches that providing nitrogen in a sintering step at 20-45 L/min allows more densely sintering as sintering temperature rises [0054]. Further, considering Xiao teaches that a nitrogen flow of 10-100 L/min as suitable conditions for binder removal (claim 6, [0025]), a range of 20-45 L/min would predictably facilitate residual binder removal, which Liu discloses controlling in the heating step (column 7 lines 31-33). 20-45 L/min is equivalent to 42.4-95.3 cubic feet per hour, which meets a range of at least 20 SCFH.
Regarding claims 2 and 3, Liu exemplifies aluminum alloy 6061 (column 4 lines 46-60, column 9 lines 18-19, 39-40, 62-63, column 10 lines 7-8), which is a 6XXX series alloy and an aluminum alloy which is a 6061 alloy, thereby meeting the additional limitations recited in both claim 2 and claim 3.
Regarding claim 4, Liu discloses that the aluminum alloy powder has a particle size in the range from about 1 micron to about 500 microns, and preferably a range from about 45 microns to about 106 microns (column 5 lines 49-55). Liu discloses reasons for why particles which are too coarse or too fine should not be used (column 5 lines 49-55). A range of about 1 micron to about 500 microns encompasses the range recited in claim 4, and a range from about 45 microns to about 106 microns overlaps the range recited in claim 4. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Regarding claims 5 and 6, Liu discloses that the densification (sintering) aid is selected from the group consisting of tin and magnesium (column 6 lines 6-11, claim 7). Tin or magnesium meet the additional limitations recited in claim 5, and tin meets the additional limitations recited in claim 6.
Regarding claim 7, Liu discloses that the sintering temperature between about 550
°
C to 650
°
C (column 7 lines 21-23), which overlaps a range from about 610 C to about 660 C. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Regarding claim 9, the nitrogen flow range of 42.4-95.3 cubic feet per hour taught by Xiao [0052-54] overlaps a range of about 5 SCFH to about [emphasis added] 40 SCFH in view of paragraph [0016] of the present disclosure. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I). Further, the 10-100 L/min nitrogen flow, which Xiao teaches as effective for binder removal ([0025], claim 6) is equivalent to 21.2-212 cubic feet per hour, and considering Liu teaches controlling heating conditions to remove binder (column 7 lines 31-33), in view of Xiao’s teachings of the effectiveness of 10-100 L/min for binder removal, a nitrogen flow rate of 10-100 L/min in a step wherein binder is removed, would have been obvious to one of ordinary skill in the art at the time of filing.
Regarding claim 10, Liu discloses an embodiment wherein the forming step is performed by binder jet additive manufacturing (3DP Process column 6 lines 35-63).
Regarding claim 11, Liu and Myers exemplify 60610 aluminum alloy (Liu column 4 lines 46-60, column 9 lines 18-19, 39-40, 62-63, column 10 lines 7-8; Myers Table I). Liu discloses tin (Sn) as a densification (sintering) aid (column 6 lines 6-11, claim 7), and the densification (sintering) aid proportion taught by Myers, applied above, comprises tin (Sn) in 1% (Table II). The 42.4-95.3 cubic feet per hour nitrogen flow taught by Xiao [0052-54], applied in the process disclosed by Liu in view of Myers and Xiao applied above is at least 20 SCFH.
Regarding claims 12-13 and 18, Liu discloses that the densified aluminum part (sintered article) has a relative density of at least about 60%; more preferably, a relative density of at least about 75%; even more preferably, a relative density of at least about 85%; and most preferably a relative density of at least about 95% (column 5 lines 30-35). Liu discloses that the parameters can be adjusted to arrive at a desired relative density (column 5 lines 23-30). The ranges of relative densities disclosed by Liu (column 5 lines 30-35) overlap a range of at least 97%, as recited in present claims 12 and 18 and a range of at least 99%, as recited in present claim 13. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Regarding claim 14, Liu discloses that forming the green part results in 30-60% of the volume of the green part of powder (printed article) (column 6 lines 47-49). As relative green density of a porous article is the volume percentage of the article which is not void space, the 30-60% volume disclosed by Liu (column 6 lines 47-49) overlaps a range of densities of a green part of about 50% to about 65%. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Regarding claims 19, Liu discloses tin (Sn) as a densification (sintering) aid (column 6 lines 6-11, claim 7), and the densification (sintering) aid proportion taught by Myers, applied above, comprises tin (Sn) in 1% of the build powder (Table II). Note that claim 17 does not exclude additional material, such as a second densification (sintering) aid, such as magnesium from the build powder.
Regarding claim 20, Liu discloses that the aluminum alloy powder has a particle size in the range from about 1 micron to about 500 microns, and preferably a range from about 45 microns to about 106 microns (column 5 lines 49-55). Liu discloses reasons for why particles which are too coarse or too fine should not be used (column 5 lines 49-55). A range of about 1 micron to about 500 microns encompasses the range recited in claim 20, and a range from about 45 microns to about 106 microns overlaps the range recited in claim 20. When claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05(I).
Claim(s) 16 and 21 is/are rejected under 35 U.S.C. 103 as being unpatentable over Liu (US7517492) in view of Myers (Myers, Neal, and Randall German. "Rapid Prototyping of Aluminum by Selective Laser Sintering." Metal Powder Deposition for Rapid Manufacturing: Proceedings of the 2002 International Conference on Metal Powder Deposition for Rapid Manufacturing. Metal Powder Industries Federation, 2002) and Xiao (CN110405214A) as applied to claims 1 and 17 above, and further in view of Hirata (US20160325356). Hirata is cited in prior office action(s).
Regarding claims 16 and 21, both Liu (column 5 lines 49-55) and Myers (page 233) teach controlling overall system particle size. While the Sn particle size taught by Myers (Table I) is sufficiently smaller than the 6061 alloy particle size taught by Myers (Table I) that the Sn particles likely would reside within spaces between alloy particles, Liu in view of Myers and Xiao does not teach specifically reasons for selecting relative particle sizes.
Hirata teaches an inkjet method for forming a part [0008], [0041-0042]. Hirata teaches forming a green part (three-dimensional shaped article) from build powder (first and second inorganic particles) and a binder (binding agent) [0008], [0009], [0020], [0025], [0041-42], [0046], [0118]. Hirata teaches that the build material comprises a first inorganic material which may be particles of an aluminum alloy powder [0045-46], [0053]. Hirata teaches that build material includes second inorganic material which may be a powder of copper, tin, lead, or silver [0008-10], [0086-88]. Hirata teaches densifying the green part by heating to sinter the part [0020], [0083], [0098]. Hirata teaches that ratio between the average particle size of the first inorganic particles and the average particle size of the second inorganic particles is in a range of 50000:1 to 10:1 [0089]. Hirata teaches that in sizing according to such a range of ratios, it is possible to allow the second inorganic particles to easily enter interstitial spaces (a void) between the first inorganic particles [0089], which renders possible an increase in density of both the first and second inorganic particles in a more uniform manner [0089], which yields a three-dimensional shaped article in which the density of the inorganic particles is increased in a more uniform manner [0089].
Both Hirata and Liu in view of Myers and Xiao teach methods for producing a densified part from a build material comprising inorganic particles and a binder.
It would have been obvious for one of ordinary skill in the art to size the densification (sintering) aid in the process disclosed by Liu in view of Myers and Xiao, applied above, such that the densification (sintering) aid resides in interstitial spaces of the aluminum alloy powder because Hirata teaches that sizing second organic particles to reside in interstitial spaces of first inorganic particles, results in an increase in density and an improved density uniformity [0089], thereby further facilitating density control in the process disclosed by Liu (column 8 lines 20-32). Densification aid residing in interstitial spaces of the aluminum alloy powder meets the additional limitations of both claim 16 and 21
Response to Arguments
Applicant's arguments have been fully considered but they are not persuasive.
Regarding rejection of independent claim 1, under 35 USC 103, over Liu (US7517492) in view of Myers (Myers, Neal, and Randall German. "Rapid Prototyping of Aluminum by Selective Laser Sintering." Metal Powder Deposition for Rapid Manufacturing: Proceedings of the 2002 International Conference on Metal Powder Deposition for Rapid Manufacturing. Metal Powder Industries Federation, 2002) and Xiao (CN110405214A), applicant argues that Liu repeatedly emphasizes the presence and importance of water vapor during the sintering process, while claim 1 recites "densifying the green part by heating the green part under a continuous flow of gas of at least 5 standard cubic feet per hour (SCFH) and to a sintering temperature between the solidus and liquid temperature of the aluminum alloy sufficient to promote reaction-assisted super-solidus liquid phase sintering, wherein the continuous flow of gas consists essentially of nitrogen, and the densified aluminum part has a density of at least 95%." This argument is not persuasive because “[f]or the purposes of searching for and applying prior art under 35 U.S.C. 102 and 103, absent a clear indication in the specification or claims [emphasis added] of what the basic and novel characteristics actually are, "consisting essentially of" will be construed as equivalent to "comprising." “ (MPEP 2111.03(III)). The speciation as filed names oxygen as a gas excluded from the gas flow in sintering [0031-32] but does not clearly indicate water vapor; therefore, the claimed “flow of gas consists essentially of nitrogen” does not exclude the water vapor disclosed by Liu.
Applicant’s statement in the remarks filed May 18, 2026 that “[a] gas atmosphere consisting essentially of nitrogen excludes deliberate inclusion of additional reactive gaseous components, such as water vapor, that would materially affect the claimed sintering process” is not supported by the specification as filed. The specification does state “[o]ther common sintering atmospheres, such as argon, hydrogen, or mixture of nitrogen and hydrogen were not effective at achieving densities of 99% or greater” in paragraph [0032], and considering argon is an inert gas, reactivity of gas atmosphere is not the basis for determining which atmosphere components do or do not materially affect the basic and novel characteristics of the invention. Further, the disclosure as filed repeatedly indicates that the sintering is reactive (reaction-assisted) (paragraphs [0011], [0023], [0035-37], noting that that the surface layer of the aluminum alloy powder particles chemically breaks down during the sintering [0023]; therefore, the sintering in the present invention does not occur in a chemically inert environment. As applicant’s arguments filed May 18, 2026 are the first instance in the file in which the presence of water vapor would materially affect the basic and novel characteristics of the invention, and applicant does not indicate how the disclosure as filed supports the interpretation in applicant’s arguments, this statement in applicant’s arguments is not sufficient to show that the disclosure as filed supports an interpretation wherein the presence or absence of water would affect the basic and novel characteristics of the material, and therefore, the statement in applicant’s arguments is not sufficient to define over the sintering environment disclosed by Liu. Paragraphs [0031] and [0032] would be sufficient to support flow of gas which consists of nitrogen, which would exclude water vapor and defining over Liu. Claim 1 does not claim the flow of gas consists of nitrogen.
Applicant argues that claims 2-7 and 9-14 define over Liu in view of Myers and Xiao by dependence on claim 1. This argument is not persuasive for the reason(s) given above with respect to claim 1.
Regarding claim 9, applicant argues that Xiao’s disclosure of 20 L/min to 45 L/min (42.4-95.3 cubic feet per hour) does not overlap a range of 5 to 40 cubic feet per hour (2.4 to 18.9 L/min). This argument is not persuasive because claim 9 claims “about 5 SCFH to about 40 SCFH”. The lower limit taught by Xiao of 20 L/min (42.4 cubic feet per hour) is about 40 cubic feet per hour (18.9 L/min); therefore, the range taught by Xiao overlaps the values of claim 9 as actually claimed, not the considerably narrower ranges which applicant argues claim 9 encompasses. Applicant is also reminded that paragraph [0016] of the present disclosure states “Unless otherwise stated, the words "about" and "substantially" as used herein are to be construed as meaning the normal measuring and/or fabrication limitations related to the value or condition which the word "about" or "substantially" modifies”. Xiao’s teaching of such a flow rate in a sintering process is more than sufficient to establish the flowrate taught by Xiao as within the normal fabrication limitations in some way related to the gas flow in a sintering step.
Applicant’s arguments that Liu does not disclose the density limitations of claims 12 and 13 are not persuasive because Liu discloses sintering “most preferably to a relative density of at least about 95%” (column 5 lines 31-35,claim 19), which encompasses the ranges recited in claims 12 and 13. The discussion in MPEP 2144.05(I) contains several instances wherein overlapping/encompassing prior art ranges for the same property were not only sufficient to establish a prima facie showing of obviousness but also required evidence to rebut the showing of prima facie obviousness. Applicant does not support the arguments regarding claims 12 and 13 with evidence commensurate in scope with the claimed that densities of “at least 97%” or “at least 99%” would have been unexpected over the encompassing prior art range of “at least 95%”. The Office Action relies on Liu for allegedly teaching the claimed density limitations. However, Liu merely discloses densities of "at least about 95%." Pointing out that “densities above 99% can be achieved by utilizing specific processing conditions, including the use of a continuous high flow of nitrogen during sintering” is not sufficient evidence because Liu discloses “the relative density of the sintered part desired will depend on the aluminum powder parameters and the application for which the sintered article is intended to be used” (column 5 lines 23-26); therefore, one of ordinary skill in the art, at the time of filing would have expected that different processing parameters yield different relative densities. Pointing to the passage in the specification that states that other common sintering atmospheres, such as argon, hydrogen, or mixtures of nitrogen and hydrogen, were not effective at achieving densities of 99% or greater, particularly is not persuasive because a mixture of nitrogen and hydrogen is a gas which “consists essentially of nitrogen”, which is what is claimed. Further, applicant does not support this assertion with the numerical values of the relative density when sintered under “other common sintering atmospheres, such as argon, hydrogen, or mixtures of nitrogen and hydrogen”, there is overlap between a range of “at least 97%” and articles which are not able to meet a relative density of 99%, and without numerical values, it cannot be determined whether or not the difference in density is unexpected to a statistical and practical significance.
Applicant argues that claims 15 and 16 define over Liu in view of Myers, Xiao, and Hirata (US20160325356) by dependence on claim 1. This argument is not persuasive for the reason(s) given above with respect to claim 1. Further, claim 15 is canceled, and a canceled claim cannot define over the prior art.
Applicant argues the rejection of independent claim 17 under 35 USC 103 over Liu in view of Myers, Xiao and Hirata by reference to limitations which claim 17 shares with independent claim 1. This argument is not persuasive for the reasons given above with respect to claim 1. Also note that applicant’s amendment has deleted from claim 17 the limitation for which prior office action(s) relied on Hirata, and the present rejection of claim 17 under 35 USC 103 is over Liu in view of Myers and Xiao.
Applicant argues that claims 18-21 define over the prior art by dependence on claim 17. This argument is not persuasive for the reason(s) given above with respect to claim 17.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SEAN P O'KEEFE whose telephone number is (571)272-7647. The examiner can normally be reached MR 8:00-6:30.
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/SEAN P. O'KEEFE/ Examiner, Art Unit 1738
/SALLY A MERKLING/ SPE, Art Unit 1738
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